1. Field of the Invention
The present invention relates, in general, to an arrangement for securing bulkhead doors employed in the compartmenting of cargo or bulk lading in a freight transport vehicle such as a railway freight car, a freight trailer, or the like. More particularly, the present invention relates to an improved locking arrangement for a bulkhead door in a railroad freight boxcar known as Palletized Shipping Program (PSP) freight car in which adjustably movable bulkhead doors are adapted to be locked in place relative to cargo or lading so as to prevent subsequent movement and damage thereto.
Palletized Shipping Program (PSP) railroad boxcars are frequently utilized in the shipment of bulk commodities, such as grain, cereals, and other types of comestibles. In view thereof, these vehicular carriers tend to be considered as mobile warehouses, and governmental regulations require that the carriers be of a design enabling the grain and other food products to be shipped in a clean and sanitary manner meeting prerequisite standards. Accordingly, a transport vehicle of this type should make provision to allow for the removal and cleaning of grains and other foodstuff residues which may serve as a harborage and breeding grounds for insects, vermin, and other pests commonly associated with food products of this nature. The transport, vehicle must be periodically cleaned or disinfected, and areas, such as hidden locations not readily accessible and which are susceptible to infestation, must be able to be effectively treated with insecticides. In prior art Palletized Shipping Program boxcars, the locking mechanisms for the movable bulkhead doors have generally been of two commonly employed designs.
2. Discussion of the Prior Art
In accordance with one prior art design, the bulkhead doors, usually two per vehicle or railroad boxcar, are locked into position against loaded cargo through the use of vertically extending lever-operated pins mounted in the doors which engage holes in bulkhead locking tracks located in and extending along each longitudinal side of the vehicle floor. A typical PSP boxcar is fifty feet in length and, in accordance with this prior art bulkhead locking arrangement, approximately 250 locking holes are formed in each locking track on each side of the boxcar, in effect, a total of about 500 holes for each boxcar. Each track includes a channel member having the locking holes spaced along its length and with the interior of the channel member being preferably filled with urethane foam to minimize cleaning and contamination problems with the track. In accordance with this approach, if a bulkhead door is to be locked in place using a particular set of locking holes, the urethane foam in those holes is removed, such as by drilling, to permit insertion of the door locking pins. With continued usage of the boxcar, those holes having the urethane foam removed therefrom cause cleaning and resultant infestation problems.
Another problem associated with this prior art approach is that the urethane foam presents an additional infestation problem in that insects and insect eggs tend to invade inner spaces where the foam meets surfaces of the floor plate or in cracks which occur in the foam. In view thereof, each track must be periodically completely stripped of its urethane foam, possibly several times each year, and then refoamed. An operation of this nature requires a partial disassembly of the PSP boxcar to obtain access to an open end of the track. The inside of the track is then blasted, as with a sandblasting technique, to remove the old contaminated urethane foam therefrom. Each track must be subsequently refilled with new urethane foam, and the transport vehicle reassembled; obviously a relatively time-consuming and expensive operation, particularly considering that each transport vehicle is not available for its primary purpose of transporting goods during this lengthy and cumbersome servicing operation.
In accordance with a second prior art design for PSP boxcar bulkhead door locking tracks, a recessed track having a series of raised pins is positioned so as to extend along each longitudinal side of the transport vehicle. A movable bulkhead door is then selectively positioned over appropriate raised pins on each side of the vehicle, thereby locking the door in place. Although each recessed track together with its series of pins is easier to clean than a vehicle constructed in accordance with the first approach employing urethane foam-filled tracks, the open tracks generally must extend the full length of the transport vehicle on each longitudinal side thereof, and the recessed areas tend to collect and trap residue such as grain and collected floor dirt, forming regions subject to insect infestation. It would be desirable to have an arrangement for locking bulkhead doors which is easily cleaned, as by vacuuming, and which may be effectively and easily treated with a minimum and safe application of insecticides.
Another disadvantage encountered in the prior art arrangements is that a damaged track must be repaired in a railroad service yard, with the attendant drawback that the vehicle is not available for freight transportation during the time interval required to effect the necessary repairs.
Brown, Jr., et al. U.S. Pat. No. Re. 27,615 discloses an arrangement for protecting lading or freight in a transport car in which the freight is secured in place by movable bulkhead doors. In this arrangement the bulkhead doors are provided with latching studs which cooperate with depressions in fixed members at the top and bottom of the car to secure the door in place against the cargo. Furthermore, the bulkhead doors are provided with inflatable cushions which may be expanded against the cargo to further assist in securing it relative to the transport vehicle.
Vander Hyde, et al U.S. Pat. No. 3,168,055 discloses an arrangement in which railroad cars are equipped with rigid bulkhead doors movably positioned on overhead tracks and latching at their top and bottom to lock the doors in place against the cargo. In this prior art arrangement, upper and lower latching pins project from the bulkhead door into latching openings formed periodically along the length of the track members to secure the door in place.